Maker types will love the idea of a smartphone with replaceable Lego-like pieces. Everyone else will buy a real smartphone

If you're old enough to have danced to Devo, you also likely remember the build-your-own-PC phenomenon that geeks like me were into, spending many weekends at parts emporia like Fry's Electronics to get that hard drive, this power supply, and the other motherboard. Dell took that concept and made a mint selling computers customized by you online, then built by the company. The 1980s were a blast!

In a return to the past, Google has been working on Project Ara, an effort to create a standard for modular smartphones that could ship as soon as a year from now. Hardware makers would provide a standard chassis, called an endoskeleton, to which you'd insert various modules and snap a screen. If you want a faster processor, you could take out and replace the existing one -- same for the battery, graphics processor, cameras, power connector, and sensor array. You could even add capabilities such as ports and dual-SIM readers by placing them in empty blocks or replacing a component with a new one that served several functions.

You can see why the DIY and Maker crowds are enthused by the idea. It's Legos for techies -- a return to the build-your-own-PC or Heathkit eras a few decades ago, when we stayed in our basements and off the streets.

To be sure, Google has some fascinating ideas in Project Ara, an outgrowth of military research into modular manufacturing for battlefield and espionage devices. The hot-swappable modules -- called Phonebloks -- are kept together through an electromagnetic lock, so they don't accidentally pop out while you're jogging. And there's a universal bus called UniPro that provides Ethernet-like speeds of up to 10Gbps distributed across the various components. A universal bus is of course necessary, since you could be connecting anything into the device.

These technologies are unproven, and they haven't been used in any consumer-scale manufacturing. However, they clearly could be relevant in various kinds of field systems, especially those requiring a device that's hard to replace but has a long, serviceable lifetime. Think oil rigs, space stations, nuclear submarines, robotic factories, and perhaps even factory car stereos.

But they seem to be -- to put it mildly -- overkill for smartphones and other such personal devices. Modularity comes with several prices, which is why consumer products rarely are modular.

Recall that the build-your-own-PC mania did not survive the popularization of the PC -- it was a geek phenomenon in a few cities. Modularity is simply too complicated for most folks. They want a phone, TV, car, computer -- not a project. We all love choice, except when we have too much of it.

Modularity also reduces optimization. It's no accident that the build-your-own-PC movement didn't make it into laptops, beyond the ability to replace a hard drive with a DVD writer or perhaps put in a larger-capacity battery. What made laptops, then smartphones and tablets, deliver on mobility while being highly functional was their highly optimized, tight integration -- custom, holistically engineered designs.